Many vehicles currently feature front-wheel drive transmissions. Recently, all wheel or four wheel drive automobiles have grown in popularity. To accommodate this growth in popularity, many vehicles that would traditionally feature front wheel drive have been equipped with all wheel or four wheel drive. Typically, these are smaller vehicles than a traditional SUV or pickup truck. Many of these vehicles feature an engine transversely mounted to the vehicle. A typical all wheel or four wheel drive system in these vehicles may feature an engine, a transmission coupled to the engine, a power take off unit coupled to the transmission, and a rear drive module coupled by a drive shaft to the power take off unit. The power take off unit typically includes a differential and is coupled to the front wheels of the vehicle. The rear drive module also typically includes a differential and drives the rear wheels.
A typical power take off unit and rear drive module may also include plurality of gear ratios. For instance, the power take off unit and rear drive module may include a normal drive gear ratio for everyday driving, a low range ratio for off-road use, for example, and a neutral position for towing, for example. The power take off unit and rear drive module must be operated in the same gear ratio. Shifting between the gear ratios in the power take off unit and rear drive module must be performed precisely to ensure the longevity of the power take off unit and rear drive module. In addition, the timing of the shift in the power take off unit and rear drive module has an effect upon vehicle occupant comfort as a poorly timed shift may result in vehicle lurching.
While present methods may meet needs, further improvement in the art is desirable.